Even if it has the same mount as the '01, I wouldn't buy one from Lexus. I was also thinking of getting one until the parts manager at my local Lexus dealer quoted me the price of $600 for the one on an RX300!!! You better off getting one from donnelly.com for around $200, but the mounting will be on the windshield.
I never found the headlights in the rear view mirror bothersome. Acutally I don't even want to use the dimming feature in my RX. The auto dimming feature prevents me from reading the headlights to know whether a police cruiser is behind me, which is bad.